Study On The Synthesis Of Phenolic Compounds By Diazotization And Tubular Hydrolysis

In fact,tubular continuous reaction is more practicality and economical than reaction in retort when diazotization and tubular hydrolysis.lt was confirmed that tubular reaction had provided with strongpoints of controlling tempterature and reaction time easily, high produce efficiency,high yield,few byproduct.In this paper, the mathod was studied that phenolic compounds was synthesized bydiazotization and tubular hydrolysis from anilines.For -this kind of -seriesreaction5,tubular reaction is very availability. By this way, 2,4-dimethylphenol, 1,3-dihydroxybezene and guaiacol were synthesized from the corresponding amines, 2,4-dimethylaniline, MPDA and 2-methoxyaniline respectively.The diazotization of 2,4-dimethylaniline was accomplished, diazotize was prepared at -5℃ temperature and enter into tubular reactor, pump flux is 100ml/h,hydrolyzation temperature is 120℃,2,4-dimethylphenol can be extracted from oil phase.We approved that entering of toluene was in favour of reducing the diazo coupling reaction,enhancing the yield,minishing the infection of reaction temperature;Using of tubular reactor was propitious to saving reaction time.The yield of the lastly method is the highest,82%.The concept of R was put' forward,which can be used in estimated the degree of reaction.R~Q curve was painted,on the basis of R~Q curve we can get the aptitude flux.2-methoxyaniline was dissolved in 30% H2SO4 adding to adequacy toluene, At 5℃ temperature NaNO2 solution was dript to the system.The diazoate was mixed with a few CuSO4 solution,which was pumped to tubular reactor, pump flux is 80ml/h, hydrolyzation temperature is 150℃, hydrolyzing.Then we gained the product, guaiacol.lt was affirmed that Using tubular reactor can save a great lot of CuSO4,yielding 90%.1,3-Dihydroxybezene was synthesized by acidity hydrolysis. At 230 ℃ temperature and on high pressure,MPDA was hydrolyzed by bisulfate ammonium or H2SO4.AS a catalyzer, H2SO4 is cheaper than bisulfate ammonium.The mole ratio of MPDA/ H2SO4/H2O was'l/2/60,corresponding to 85.7% 1,3-dihydroxybezeneyield,Biit this process requires high temperature and strong acid catalystsThe combination of low pH and high temperature make the hydrolysis process dangerous and requires the use of non-corrosive materials to withstand these severe processing conditions.So we studied the method of by diazotization and hydrolysis.The diazoate was hydrolyzed in the tubular reactor,pump flux is 120ml/h,hydrolyzation is 120 ℃.Compared to acidity hydrolysis,the latter mathod economized energy sources and equipment.Purity of the productwas checked by HPLC analysis and showed above 99%,corresponding to a resorcinol yield of 79.4%.